Method of forming magnetic chucks.



L. W. DOWNESASL R. C. PATTON.

METHOD OF FORMING MAGNETIC CHUCKS. APPLICATION FILED SEPT. 12, 1916.

1,254,664. Patent Jan. 29,1918.

2 SHEETS-SHEET I.

59.1 a H m L. W. DOWNES & R. C. PATTON.

METHOD OF FORMING MAGNETIC ()HUCKS.

APPLICATION FILED SEPT- 12, I916- I Patented Jan. 29,1918.

2 SHEETS-SHEET 2 Lea/131d flaw/Zest UNITED STATES PATENT OFFICE.

LOUIS W. DOWNES. AND RALPH CLIFTON PAT'ION, OF PROVIDENCE, RHODE ISLAND,ASSIGNOBS TO D & W FUSE COMPANY, OF PROVIDENCE, RHODE ISLAND, A CORPO-unon or 2.1mm? ISLAND.

METHOD OF'FOBMING MAGNETIC CHUCKS.

lpecifieatlon of Letters Patent. Patented Jan. 29, 1918.

Application filed September 12, 1918. Serial No. 119,768.

bers being a thin web indicated in dotted To all whom it may concern:

Be it known that we, LOUIS W. Dowmzs and RALPH CLIFTON PATTON, citizensof the United States, and residents of the city of Providence, in thecounty of Providence and State of Rhode Island, have invented certainnew and useful Improvements in Methods of,

Forming Magnetic Chucks, of which the following 1s a specification.

This invention relates to an improved method of forming magnetic chuckswhich are more particularly designed for holding a multiplicity of smallpieces of work while being operated upon, but the chuck of our improvedconstruction may be employed for holding work of any form.

The object of th1s invention is to facilitate the construction of such achuck or more particularly the face plate portion of the chuck, whichplate is provided with a plurality of alternate flux carrying membersand non-magnetic gaps between its center pole and its outer fluxcarrying frame, whereby the undesirable leakage of magnetic flux presentin all types of this class of chucks, which results in a loss of holdingpower is reduced to the very minimum. This face plate is preferablyformed separate and independent from the body portion of the chuck andis removably secured thereto.

With these and other objects in view, the invention consists of certainnovel features of construction, as will be more fully described, andparticularly pointed out in the appended clalm.

In the accompanying drawings:

Figure 1- is a plan view showing the face of the chuck and thearrangement of the alternate flux carrying members and magneticinsulations separating the center pole from the outer frame or otherpole.

Fig. 2- is a side elevation partly in section illustrating theconstruction whereby the face plate is formed separate and subsequentlysecured to the body of the chuck.

Fig. 3- is a sectional view on line 3-3 of Fig. 1.

Fig. 4- is a perspective view of the. under side of the face plateshowing the outer frame, the central core and the intermediate fluxcarrying members all cast together as a single unit, the connectionbetween the memlines on the lower edge thereof.

Fig. 5 is an enlarged sectional view taken on line 5+5 of Fig. 4 showingthe grooves cast in the face plate and also show-. in the lockin tiebars passing through the di erent mem ers.

Fig. 6 is the same as Fig. 5 but showing the filler of non-magneticmaterial as having been poured into and filling the grooves about thebars, locking the whole together.

Fig. 7 shows the face late with the bottom web removed in finis ing, theplate being now ready to be positioned on the body portion of the chuck.

Referring to the drawings, 10 designates the body portion of the chuckconstructed in the form of a trough-shaped receptacle and formed of maetic flux carryin material such as cast iron or the like. 11 the middleportion of this body is formed a core 11 of different material such aswrought iron or the like, for the purpose of increasing the magneticmfluence or action of the chuck upon the work. This central core ispreferably connected to the base or the body portion by being casttherein.

A suitable magnetic wire coil 12 is carried in this frame 10 and is laidabout this central core 11.

A feature of our improved chuck is in the construction of the face plate13. This plate is preferably formed separate and independent of the bodyportion of the chuck, and comprises essentially an outer frame member14, a central pole member 15 and a plurality of intermediate independentnesting magnetic flux conducting frames or rings 16 spaced apart and setone within and I insulations into the center pole member 15,

whereby all of these members are rigidly locked together to prevent hemfrom bemg forced out of position, even if a piece of heavy work shouldhe accidentally dropped upon the face of the chuck. After this faceplate has been formed and finished on its top and bottom surfaces, it issecured to the body portion by screws 19 or other suitable.

central pole and the outer flux vcarrying frame is reduced to-theminimum. When the work, which is frequently in small pieces, isdistributed about the face of the chuck in such a manner as to bridgethe gaps, the magnetic flux travels upward through the core 11,central'pole 15 across the work a as it bridges the gaps, into thedifferent intermediate frames and then i 1 down through the outer wallof the body portion as best illustrated by the arrows in Fig. 3.

When work is placed on the chuck in such a way that a portion only ofthe entire number of gaps are bridged, then the total flux will traversethis work and the reluctance of the magnetic circuit is lessened inproportion to the number of non-magnetic gaps so brid ed.

W en no work is on the chuck face, the total amount of-leakage must beacross the several gaps in series.

It is found in practice in some instances, particularly where theintermediate frames are straight, that narrow straight bars of the sameor less Width than the frames placed upon the chuck to be operated upon,would not be held firmly, as the work must bridge one or more of thegaps to be afiected by the magnetism.

In order to obviate this difficulty, we have formed these frames so thatportions of them are sinuous or arranged to follow a zigzag coursecapable of operating more efl'ectively upon the work of a greatervariety of shapes.

Our present invention consists in the provision of a new and improvedmethod of forming the chuck and more particularly the face plate of thechuck, which is that of constructing the same by casting the outer frame14, the central pole 15 and the plurality of intermediate frames 16 allin one piece and connecting them at one edge by a thin web 20 all asillustrated in Figs. 4: to 7 inclusive. Such a casting when taken fromthe mold will be in reality a face plate having a number of deep groovesformed in one side thereof. The next step in the operation is to drill,cast or otherwise provide holes 21 through all of these members andinsert the pins, bars or other members 18 therein, then manentlytogether. The plate will then be machined on both sides to provide truesurfaces. The connecting web which is merely for the sake of holding theparts in spaced apart relation while being cast and filled,

will in the finishing operation be removed thereby separating thecentral pole 15 from the outer frame 14 by a plurality of alternate fluxcarrying frames and non-magnetic portions.

By this method of construction it will be seen that this face plate maybe formed with its plurality of separated flux carrying members in avery simple, practical, elfective and yetinexpensive manner.

We have described the various steps in our method of forming the chuckplate but their order of recitation need not necessarily be followed asin some cases the pins or lock bars may be inserted after thenon-magnetic filling has been flowed into the grooves, if desired.

Having thus described one illustrative embodiment of our invention andthe best mode known to us for carrying out our method, we desire it tobe understood that although specific terms are employed they are used ina generic and descriptive sense and not for the purpose of limitation,the scope of the invention being limited only by the appended claim.

We claim:

An improved process of constructing a magnetic chuck member whichconsists in molding an outer frame and a central pole member and aplurality of intermediate flux carrying frames all as one integral pieceby connecting them on one edge by an integral Web thereby forming aseries of deep grooves between said members, inserting a plurality ofsupporting tie bars of low magnetic permeability through all of saidmembers, introducing a filling of non-magnetic material into saidgrooves causing it to flow about said bars and so lock itself and allthe parts permanently in position, and subsequently removing said web toseparate said members magnetically.

In testimony whereof we alfix our signatures in presence of twowitnesses.

LOUIS W. DOWNES. RALPH CLIFTON PATTON. Witnesses:

WILIABD S. SISSON, GEORGE W. STEERE.

